... a triangular box about 5" longer than my tripod. It had been used to ship big rolls of drymounting tissue, and was, at one time, a product marketed by the US Post Office to ship rolls of paper, architechtural plans, blueprints, etc.
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Another choice could be the poly-vinyl chloride (PVC) lengths of pipe, fitted with screw-in ends. Lots of people use them here for carrying things around. It should be possible to have them made to any length, up to five or ten metres, being the length of a section of pipe. I've seen them used by students for carrying rolled drawings, and longer ones mounted on vehicle roof racks.
A saddler would have no trouble making a handle from harness material, stitched around the pipe in two places.
&i (: